Coating apparatus



p 1963 R. L. WALSH 3,104,824

COATING APPARATUS Filed Oct. 25, 1961 lnven for Pic/Zara L. Walsh 55//2l'5 A tzorizey United States Patent 3,104,824 COATING APPARATUSRichard L. Walsh, Newburyport, Mass., assignor, by

mesne assignments, to United Shoe Machinery Corporation, Boston, Mass.,a corporation of New Jersey Filed Oct. 25, 1961, Ser. No. 147,613 3Claims. (Cl. 239-407) This invention relates generally to apparatus forcoating surfaces and has particular reference to the coating of asurface such as the side wall of a building and to a spray apparatus forapplying said coating.

With the developments of new types of resins, such as polyurethanes andepoxys, having adhesion and weathering qualities superior to previouslyknown coating resins, it has become feasible to utilize organic coatingmaterials to apply Weather resistant coatings to buildings havingmasonry exterior surfaces such as brick, cement, stucco and stone. Toreduce the cost of the coating, and to provide various surface texturesand colors, it is usually desirable to mix with the resin a particulatematerial such as sand, quartz, mica, glass beads, roofing granules orthe like.

For speed of application, it is desirable to apply the coating by meansof spray apparatus in which the resin and the particulate material aredirected toward the surface simultaneously, with the resin andparticulate material mixing in mid air, so that the individual particlesreceive a coating of resin before they impinge onto the wall. However,this method of applying the coating has been found to have certaindifficulties that make it impractical for use in many applications. Theweight and volume of the particulate material requires that it be storedon the ground and lifted to the spray gun in an air stream and projectedby said air stream out of the gun toward the Wall surface. The velocityso imparted to the particulate material causes a substantial proportionthereof to rebound oif the wall without adhering. The material so wastednot only increases the raw material cost but also increases the hazardsof the operation, since the wasted particles, in falling to the ground,may be blown about by the Wind and damage adjacent buildings,automobiles and the like.

Another problem encountered in the application of such coatings is thefact that the particulate material frequently carries with it anundesirable amount of dust and particles below the desired size, whichtends to impair the appearance of the coating.

In my copending application Seral No. 99,142, filed March 29, 1961 thereis disclosed a method and apparatus for applying such coatings so assubstantially to reduce the amount of particulate material wasted byrebounding off the wall. Although the apparatus and method disclosedtherein is satisfactory for applying coatings in which the particulatematerial is composed of relatively fine particles, it has been foundthat the amount of material rebounding from the wall is a function ofparticle size and in some cases, where it is desired to applyparticulate material of a larger size, an excessive amount of materialrebounds from the wall and is wasted.

The object of the present invention is to provide apparatus for applyinga coating of the type described in which the velocity of the particulatematerial is reduced in passing through the spray gun to reduce theamount of particulate material rebounding from the wall.

A further object of the invention is to provide an apparatus of the typedescribed in which means is provided for separating a portion of the airused to lift the particulate material to the gun from the stream ofparticulate material substantially to reduce the velocity thereof beforeit issues from the gun.

A further object of the invention is to provide an apparatus of the typedescribed in which means is provided for separating dust and particulatematerial below the desired particle size from the particulate materialbeing directed toward the surface to be coated. Other objects of theinvention will be apparent to one skilled in the art from the followingdescription of a specific embodiment thereof.

In the drawing:

FIG. 1 is a top plan view of a spray apparatus embodying the features ofthe invention;

FIG. 2 is a view of the apparatus of FIG. 1 as seen from the left side;and

FIG. 3 is a view in section taken on line 33 of FIG. 1.

Referring to the drawing there is illustrated an apparatus 10 forapplying a coating comprising a liquid component 12 such as a syntheticorganic resin vehicle and a particulate material 14 such as sand to asurface, such as the wall of a building or the like.

The apparatus 19 includes a spray gun 17 similar to that shown in theabove-identified application and comprises a frame 18 with a downwardlyextending hand grip 20 having an air manifold 22 on the upper endthereof with an air connection 24 on the rear end to receive an airsupply hose 26. A resin spray nozzle 28 is disposed on each side of theair manifold and the nozzles are connected to a resin manifold 29 byconduits 30. The resin manifold 29 may be supplied with resin underpressure through a rear connection 31.

A sand discharge nozzle 32 is disposed on the frame and the illustratedembodiment extends through the air manifold 22 and is supported thereby.The rear end of the sand supply nozzle is provided with a connection 34receiving a T 36 onto the rear end of which may be attached a sandsupply tube 38. Extending from the side branch of the T 36 is an airdischarge tube 40 which extends upwardly and then turns forwardly toterminate in a discharge end disposed above the frame of the gun. Toprovide means for regulating the amount of air permitted to dischargefrom the tube 38, a valve 42 may be provided in the tube 40. A supply ofsand or other particulate material may be lifted to the gun in an airstream through the supply tube 38 in the usual manner so that the sandis discharged from the tube 38 into the converging resin streams priorto impingement onto the wall as described in the above-identifiedapplication.

During operation of the gun the velocity of the sand particles enteringthe gun from the supply hose will depend on several factors among whichare the pressure of the air source and the height of the gin above theair source, which in the normal case is a compressor stationed on theground. As the coating operation proceeds either up or down the wall thevelocity of the particles entering the gun will decrease or increaserespectively, but in any case the air velocity required to liftefficiently relatively large particles will cause said particles to havea considerable velocity issuing from the gun.

To reduce the amount of rebound from the wall, the valve 42 may beopened to permit a portion of the air to exhaust through the tube 40thereby reducing the velocity of the remaining portion of air carryingthe sand particles through the gun.

Since the air discharge tube 40 opens to the upper side of the sandsupply tube 38 there is little or no tendency for the particles to passout through the tube 40 due to the effect of gravity and the inertia ofthe particles as they pass the opening to the tube 40. The velocity ofthe particles issuing from the gun may be readily controlled byadjustment of the valve 42 to compensate for variations in air supplypressure and variations in the height of the gun above the ground toreduce to a minimum the amount of particles rebounding from the wall.

The particulate material applied to the Wall frequently contains someundesirable amount of dust and particles finer than that desired to beapplied to the wall. The use of the air discharge tube 40 has been foundto have the additional advantage in that a substantial portion of thisundesirable material tends to pass out through the tube 4%) with theexhausted air since it has less mass and inertia than particles of thedesired size.

In the illustrative embodiment the tube 4% is directed forwardly so thatthe dust issuing therefrom is directed away from the operator. Since thegun is normally held an appreciable distance away from the wall, usuallyabout two feet, the dust issuing therefrom does not reach the wall butis di used into the atmosphere. It will be understood that the tube 40may be made flexible so that the discharge thereof may be in anyconvenient direction or in some cases may be discharged into a filterbag.

Since certain other obvious changes may be made in the device withoutdeparting from the scope of the invention, it is intended that allmatter contained herein be interpreted in an illustrative and not in alimiting sense.

Having thus described my invention, What I claim as new and desire tosecure by Letters Patent of the United States is:

1. An apparatus for applying particulate material to a surfacecomprising means for receiving said particulate material in an airstream having a velocity which is variable in accordance with thechanges in conditions normally encountered during use of said apparatus,means for directing said air stream and the particulate materialreceived therein toward said surface, means for exhausting a substantialportion of said air stream Without exhausting any appreciable portion ofsaid particulate material prior to the ejection of said particulaternatenial from the directing means to reduce the velocity to which saidparticulate material is ejected from said directing means, and means foradjustably regulating the rate of exhaustion of said air stream by saidexhausting means to thereby maintain the velocity at Which saidparticulate material is ejected from said directing means at asubstantially constant component comprising a particulate material, saidapparatus comprising a spray gun having means for projecting the liquidcomponent toward the surface, and conduit j means on the gun adapted toreceive the particulate material in an air stream and direct it into theliquid component as it issues from the gun, and air by-pass meansassociated with said conduit means for exhausting a substantial portionof the air stream from the particulate material to reduce the velocitythereof prior to issuance'from the directing means.

3. An apparatus for applying to a surface a coating comprising a liquidcomponent and a separately applied component comprising a particulatematerial, said apparatus comprising a spray gun having means forprojecting the liquid component toward the surface, and conduit meansassociated with the gun adapted to receive the particulate material inan air stream and direct it into the liquid component as it issues fromthe gun, and 'an air discharge tube extending laterally from saidconduit to release a portion of the air from said air stream to therebyreduce the velocity of said particulate material, and means forregulating Q the amount of air flow through said air discharge tube.

References Cited in the file of this patent UNITED STATES PATENTS

2. AN APPARATUS FOR APPLYING TO A SURFACE A COATING COMPRISING A LIQUID COMPONENT AND A SEPARATELY APPLIED COMPONENT COMPRISING A PARTICULATE MATERIAL, SAID APPARATUS COMPRISING A SPRAY GUN HAVING MEANS FOR PROJECTING THE LIQUID COMPONENT TOWARD THE SURFACE, AND CONDUIT 